Conventionally, an ultrasound diagnosis apparatus emits ultrasound wave pulses generated by ultrasound transducer elements provided in an ultrasound probe to the inside of an examined subject and receives reflected-wave signals from a tissue of the subject through the ultrasound transducer elements. Further, the ultrasound diagnosis apparatus generates image data from the reflected-wave signals and generates and displays an ultrasound image generated from the image data.
Various types of image filters are applied to the image data for the purpose of reducing noise and speckles, or the like. For example, an image filter detects edge sizes and directions as feature amounts of an image and smooths the image or controls the degree of enhancement on the basis of the detected directions.